The invention concerns a switching device of a two stage planetary gear.
A basic, generic form of shifting devices was made known) from the operating specification 4161 758 002b for two-stage shifting devices for xe2x80x9cAC and DC Main Spindle Drive, 2K10, 2K12, 2K15, 2K20xe2x80x9d of the ZF Maschinenantribe, GmbH, February, 1994. The gear drive has been mainly used in tool machine drives for turning, milling, and machining centered Industries. DC/AC-main spindle motors serve as primary driving means. The gearing sets increase the band width of application of the main spindle motors by increasing the flexibility of the tool machines in the working of various starting materials, that is, by increasing cutting power through high torques or speeds of rotation. The two ratio change stages are formed, in that first, the input shaft, which is connected to a sun gear, is also coupled to a hollow internal gear and second, the said hollow gear is coupled with the housing. A planetary gear carrier is attached to the output shaft.
A sliding collar serves as an axially movable connection piece between the internal gear and the sun gear, which is to say, between the internal gear and the housing. This said collar is connected by means of a forked switching member with an electrical limit switch unit. This encompasses a helical drive land a slip clutch and is driven by a direct current motor, which is placed axis-parallel to the input shaft and extends at the end above the gear drive housing. The helical drive converts the rotating motion to a vertical movable shifting shaft, which by means of a pinion and toothed bar, converts the rotating motion into a linear movement. This is transmitted over a shifting element to the sliding collar. For the recognition of end-positions, two limit switches serve In the circuit unit, which must be installed in the wiring, together with the end position detent. The shifting equipment is complex and expensive and It Is difficult to adjust this to match spatial and drive aspects of application requirements.
Further, from DE 196 28 642 C2, an electro-mechanical shifting mechanism for change of gear transmissions for motor vehicles is made known, wherein an armature of an electromagnet acts upon a slide collar by means of a shifting disk serving as a linkage lever. The shifting disk can be placed in several shifting positions by means of a locking magnet. The activation rod of the armature can also coact directly on a fork of the slide collar.
From DD 33 668, especially for motor vehicles, there is made known an electromechanically controlled shifting apparatus for gear change transmissions. Two springs center a gear shifting member into its middle position by means of two armatures of two electromagnets. By appropriate, varying control of the electromagnets, two other shift lanes can be preselected and positioned. Since the electromagnets, when in the switched-on condition, work against two springs, the current demand in the ON-condition is substantial and the efficiency is not satisfactory.
Thus the invention has the purpose, of creating a simple shifting apparatus, which, without great expense can be adapted to various applications and operational conditions.
In accord with the invention, the positioning member is an electromagnet, the armature of which is driveably connected to a slide collar. Since the electromagnet, in comparison to a helical gear drive, possesses no inherent friction, it is advantageous that the electromagnet does possess detent means, which lock the armature in the shifting positions. These detent elements can be spring loaded ball elements. In order to increase the security, it is of advantage however, if locking magnets be employed as detent elements, by means of which, a form-fit secured position can be obtained.
The electromagnet is advantageously installed on the periphery of the gear drive housing, axis-parallel to the input shaft and to the direction of shifting. Its length should not extend beyond the housing of the narrowly built planetary gear arrangement, so that the gear drive can be conflict with electromotors of different diameters which, in some cases can extend beyond the cross-sectional contour of the gear drive housing. Further, with an electromagnet, short shifting times can be obtained.
In accord with an embodiment, between the electromagnet and the slide collar, a two-armed lever is provided, which is pivotally fastened in mid-section to the gear drive housing and is connected by one arm to the armature and with the other arm on the slide collar. By means of different lever arms, the shifting force and the shifting path can be modified. When this is done, it is advantageous, to place an adapter piece between the gear drive housing and the electromagnet, in which the lever is secured. Thereby, the range of variation of the lever relationships can be clearly increased.
In order to reduce the friction between the lever and the slide collar, it becomes necessary that the said slide collar has an outer and an inner part. The outer part is affixed by a an axial guide bolt to resist turning, and is guided axially to slide on the gear drive housing and provided with a roller bearing to be pivotally secured on the inner part. Thus there exists between the lever and the outer part of the slide collar no rotational movement between them, which could act upon the shifting force. The inner part, which is compelled to execute the axial movement, possesses an outer coupling toothing for coupling onto the gear drive housing and an inner toothing for a driveable connection with the sun gear.
Since the electromagnet is inclusive of a limit detent, the end limit switch can be dispensed with and need not be installed again. By means of these measures, improper positioning and possibilities of error on the part of the end user are avoided. For security, it is, however of advantage, to provide an end limit switch to monitor the shift position and the shift functioning, although these need not be adjusted.